JP7354716B2 - Laser radar equipment and lenses for laser radar equipment - Google Patents

Description

The present invention relates to a laser radar device and a lens for a laser radar device.

A laser radar device that detects an object by outputting a laser beam from a light emitting element and detecting the reflected light of the laser beam by a light receiving element uses a light receiving lens to guide the reflected light to the light receiving element. There are some that are configured to do so. By increasing the amount of reflected light (light reception amount) that reaches the light receiving element using the light receiving lens, it is possible to contribute to improving object detection accuracy.

As this type of laser radar device, a bifocal laser radar device has been proposed in which a light-receiving lens is provided with a long-distance lens portion and a short-distance lens portion, respectively. Specifically, the long-distance lens part and the short-distance lens part are made into rotationally symmetrical curved surfaces (for example, aspherical) about the light-receiving axis of the light-receiving lens, so that the reflected light from a long distance is reflected from a long distance. By adopting a configuration in which the light is focused on the light receiving element through the lens section for short distances, and the reflected light from a short distance is focused on the light receiving element through the lens section for short distances, the object detection range can be expanded. (For example, see Patent Document 1).

Japanese Patent Application Publication No. 2000-186928

In the above-mentioned bifocal laser radar device, the focal points of the long-distance and short-distance lens sections are determined according to the assumed distance to the object. For this reason, the reflected light from objects located at a long distance that enters the lens section for short distances, and the light reflected from objects located at a short distance that enters the lens section for long distances. It is assumed that it will be difficult to reach the light receiving element. In other words, although the above configuration is preferable for reducing the difference in the amount of reflected light from each distance, the overall decrease in the amount of received light may impede the expansion of the object detection range. As described above, there is still room for improvement in the optical system of a laser radar device in order to widen the object detection range.

The present invention has been made in view of the above problems, and its main purpose is to provide a laser radar device or a lens for a laser radar device that can suitably widen the object detection range. .

Below, means for solving the above problems will be described.

First means. A light projecting section that projects a laser beam, a light receiving section that has a lens that collects reflected light that is the laser light reflected by an object, and a light receiving element that receives the reflected light that is focused by the lens. , a laser radar device configured such that the light receiving axis of the light receiving section and the light emitting axis of the light projecting section are non-coaxial,
The lens includes:
a long-distance lens portion that has a curved surface that is rotationally symmetrical about the light-receiving axis and can guide reflected light parallel to the light-receiving axis to the light-receiving element;
The light receiving element has a cylindrical shape centered on a center line that intersects a straight line parallel to the light receiving axis, and a part of the reflected light parallel to the light receiving axis and a part of the reflected light not parallel to the light receiving axis are transferred to the light receiving element. A short-distance lens part that can be guided to is provided.

The further away an object is from the laser radar device, the easier it is for laser light (reflected light) reflected by the object that forms a smaller angle with the light receiving axis to reach the lens. In other words, for reflected light from an object that is located far away from the laser radar device, when it reaches the lens (incidence surface), its direction will be approximately parallel to the receiving axis, and the light will be located close to the laser radar device. When light reflected from an object reaches the lens (incidence surface), the angle it makes with the light receiving axis tends to become large. Note that "substantially parallel" refers to a case where the angle (angle formed) with respect to the light receiving axis is large enough to allow light to be received.

The long-distance lens has a curved surface (for example, an aspherical surface) that is rotationally symmetrical about the light-receiving axis. It is guided to the light receiving element by the distance lens section. On the other hand, the short-distance lens portion has a cylindrical shape with its center line oriented in a direction intersecting the axial direction of the light receiving axis. In other words, the short-distance lens portion is not provided with curvature in the same direction as the center line (center line direction or generatrix direction). Therefore, it is possible to prevent the direction of reflected light that is not parallel to the light-receiving axis from changing significantly before and after passing through the lens and deviating from the light-receiving element. This can contribute to improving the light reception efficiency of the reflected light (non-parallel reflected light) incident on the short-distance lens section. Further, the near-distance lens section is provided with a curvature in a direction perpendicular to the center line, and a portion of the reflected light parallel to the light receiving axis is guided to the light receiving element. This is advantageous in increasing the amount of reflected light that reaches the short-distance lens section from a long distance.

In this way, reflected light from a short distance can reach the light-receiving element through the short-distance lens part, while reflected light (parallel light) from a long distance can also reach the light-receiving element through the short-distance lens part. By adopting a structure that can be guided and suppressing the presence of the short-distance lens section from being a factor that greatly reduces the amount of reflected light received from a long distance, the detection range of objects can be expanded in bifocal laser radar devices. can be suitably realized.

Note that it is preferable to make the short-distance lens part cylindrical in order to suppress the expansion of the field of view for receiving reflected light and to suppress a decrease in detection accuracy due to the influence of external disturbances and the like.

Incidentally, the description ``a long-distance lens part that has a rotationally symmetrical curved surface shape about the light-receiving axis and is capable of guiding reflected light parallel to the light-receiving axis to the light-receiving element'' is replaced by ``centered around the light-receiving axis''. The first lens part has a rotationally symmetrical curved surface shape and is capable of guiding reflected light parallel to the light receiving axis to the light receiving element, and has a center line that intersects with a straight line parallel to the light receiving axis. "a short-distance lens part that has a cylindrical shape and can guide a part of the reflected light parallel to the light-receiving axis and a part of the reflected light non-parallel to the light-receiving element to the light-receiving element." "It has a cylindrical shape centered on a center line that intersects a straight line parallel to the light receiving axis, and a part of the reflected light parallel to the light receiving axis and a part of the reflected light not parallel to the light receiving axis are received by the light receiving axis." It may be changed to a second lens portion that can be guided to the element.

Second means. The light receiving axis is offset in a predetermined direction (e.g., vertically) with respect to the light emitting axis, and the center line of the near distance lens portion is offset from the light emitting axis and the light emitting axis. It is formed to intersect both of the light receiving axes.

Reflected light from an object located at a short distance obliquely enters the short distance lens section from the light projecting section side (light projecting axis side). Here, since the short-distance lens part does not have a curvature in a predetermined direction, the direction of the reflected light incident obliquely changes significantly before and after passing through the lens, and it can be suppressed from deviating from the light receiving element. . In this way, the positional relationship between the light emitting axis and the light receiving axis is determined so as to be offset in a predetermined direction, and the orientation of the short distance lens section is determined so that the center line intersects both the light emitting axis and the light receiving axis. By doing so, it is possible to further suitably widen the object detection range.

Third means. The lens is a plano-convex lens, the convex surface of which constitutes the incident surface of the laser beam, and the short distance lens portion is formed to be convex on the same side as the incident surface.

By forming the short-distance lens part so that it is convex on the same side as the incident surface, and by making the light-receiving element side flat, the lens can be made to reflect light that passes through the short-distance lens part in the above-mentioned predetermined direction. It can function like a flat plate whose direction (tilt) does not change. With such a configuration, it is possible to suppress a large change in the direction of reflected light before and after passing through the lens.

Fourth means. The lens is configured such that the center line of the short-distance lens section and the light receiving axis line are orthogonal to each other, and the focal point of the long-distance lens section is located in a linear condensing range of the short-distance lens section. It is configured.

The focal point of the cylindrical short-distance lens portion is linear. As mentioned above, if the center line and the receiving axis (light emitting axis) are made perpendicular to each other, and the focal point of the long-distance lens section is positioned on the focal point of the near-distance lens section, reflection from a short distance can be avoided. This is advantageous in efficiently receiving light and reflected light from a long distance.

Fifth means. Between the light receiving element and the lens, a part of the reflected light guided to the light receiving element by the short distance lens part, which is reflected light from a predetermined distance included in the short distance, is blocked. A diaphragm portion is provided for reducing the amount of reflected light that reaches the light receiving element.

Some laser radar devices have a structure in which, for example, a light projecting section and a light receiving section are housed in a case body, and a laser beam is emitted through a transmission section provided in the case body. In such a configuration, if the laser light reflected by the transmitting part reaches the light receiving element, the amount of light received will jump significantly, increasing the possibility of false detection as if an object were present near the laser radar. Furthermore, when measuring the distance to an object based on the amount of received light, the reliability of the distance measurement result decreases. Therefore, if a configuration is adopted in which part of the reflected light from a very close distance (transmission part) is blocked as described above, the occurrence of the above-mentioned inconvenience can be suitably suppressed.

Sixth means. The short-distance lens section is arranged such that at least a part of the short-distance lens section is located at a portion of the laser beam incident surface of the lens that is closer to the light emitting section than the light receiving axis. ing.

When a configuration is adopted in which reflected light from a short distance reaches the light receiving element through a cylindrical short distance lens section, the short distance lens section is placed in the part of the lens that is closer to the light emitting section than the light receiving axis as described above. By configuring the structure in which at least a portion of the light is located, it is possible to suitably improve the light receiving efficiency of reflected light from a short distance.

Seventh means. A convex portion that is convex on the side opposite to the light-receiving element is formed on the incident surface of the laser beam of the lens, and at least a part of the top of the convex portion serves as the short-distance lens portion. ing.

In a configuration in which reflected light is guided to a light-receiving element by a lens, light-receiving efficiency may decrease due to increased manufacturing errors. Such concerns are expected to become stronger as the shape of the lens becomes more complex and molding becomes more difficult. In this regard, if a convex part is formed on the entrance surface of the lens as described above, and the short-distance lens part is disposed on the top of this convex part, for example, a concave part is formed on the entrance surface and the bottom part of this concave part is arranged. Molding is easier than in the case of forming a short-distance lens part. Thereby, it is possible to suitably eliminate concerns caused by the combination of the long-distance lens part and the short-distance lens part.

In addition, by making the side surface of the convex part a total reflection surface that totally reflects reflected light from a short distance toward the light receiving element, it is possible to suppress the decrease in light reception efficiency of reflected light from a long distance while also reducing reflected light from a short distance. This can contribute to improving the light receiving efficiency.

Eighth means. The light receiving axis is offset in a predetermined direction with respect to the light emitting axis,
The convex portion has a cylindrical shape centered on the light receiving axis,
The top portion of the convex portion has a portion on the side of the light emitting axis with respect to the light receiving axis as the short distance lens portion, and a portion on the opposite side of the light emitting axis with respect to the light receiving axis as the short distance lens portion. It is formed to be a long-distance lens part,
The side surface of the convex portion functions as a total reflection surface that totally reflects reflected light from a short distance toward the light receiving element.

According to the above configuration, the outer diameter of the convex portion can be increased while suppressing the enlargement of the short-distance lens portion. This is preferable in order to improve the light receiving efficiency of reflected light from a short distance while suppressing a decrease in the light receiving efficiency of reflected light from a long distance.

Ninth means. A scanning laser radar device that projects a laser beam to an irradiation angle set for each predetermined angle,
The light receiving axis is offset in a predetermined direction with respect to the light emitting axis,
The predetermined direction and the direction of the center line of the short-distance lens section are configured to be a specific direction orthogonal to the scanning direction of the laser beam.

By making the center line of the cylindrical short-distance lens part perpendicular to the scanning direction, it is possible to suppress the expansion of the field of view in the scanning direction. By suppressing the expansion of the field of view, it is possible to suppress false detection of objects due to external disturbances, etc., and contribute to improving the accuracy of detecting the position of objects in the scanning direction.

Tenth means. It includes a light projecting section that projects a laser beam, and a light receiving section having a light receiving element that receives reflected light that is the laser light reflected by an object, and a light receiving axis of the light receiving section and a light projecting axis of the light projecting section. A lens for a laser radar device that is applied to a laser radar device configured such that the reflected light is non-coaxial and that can guide the reflected light to the light receiving element in a condensing manner,
a long-distance lens portion that has a curved surface that is rotationally symmetrical about the light-receiving axis and can guide reflected light parallel to the light-receiving axis to the light-receiving element;
It has a cylindrical shape centered on a center line that intersects a straight line parallel to the light-receiving axis, and guides a part of the reflected light parallel to the light-receiving axis and a part of the reflected light directed toward the center line to the light-receiving element. A possible short-distance lens section is provided.

By using the above-mentioned lens for a laser radar device, it is possible to suitably widen the detection range of an object in a bifocal laser radar device. Further, it is preferable to form the short-distance lens portion into a cylindrical shape in order to suppress the expansion of the field of view for receiving reflected light and to suppress a decrease in detection accuracy due to the influence of external disturbances and the like.

FIG. 1 is a schematic diagram showing a laser radar unit in a first embodiment. Schematic diagram of the optical block viewed from the side. Schematic diagram of the optical block viewed from the front. A side view of the light receiving lens. FIG. 3 is a cross-sectional view of the light-receiving lens (partial cross-sectional view taken along line AA in FIG. 3). FIG. 3 is a vertical cross-sectional view of the light receiving lens (partial cross-sectional view taken along line BB in FIG. 3). A schematic diagram showing the functions of a short-distance lens section. (a) A schematic diagram showing how reflected light is received from a long distance; (b) A schematic diagram showing how reflected light is received from a short distance. A schematic diagram showing a comparative example of a light receiving lens. (a) A schematic diagram showing the relationship between the distance to an object and the amount of received light; (b) A partial enlarged view showing a close-range portion in FIG. 10(a). FIG. 3 is a schematic diagram showing a laser radar unit in a second embodiment. (a) A schematic diagram showing the relationship between the distance to an object and the amount of received light; (b) A partial enlarged view showing a close-range portion in FIG. 12(a). Schematic diagram showing a modified example of the light receiving lens.

<First embodiment>
The first embodiment will be described below with reference to the drawings. This embodiment is embodied as a laser radar device including a laser radar unit and a control device for the laser radar unit. First, the outline of the laser radar unit will be explained with reference to FIG.

As shown in FIG. 1, the laser radar unit 20 is an optical system that outputs a laser beam at an irradiation angle set for each predetermined angle (for example, 0.25°) and receives the laser beam reflected by an object S. It includes a mechanism 30 and a housing 50 that constitutes the outer shell of the laser radar unit 20, and is fixed to a fixed object 100 such as a wall surface via a mounting plate.

The housing 50 is made up of a combination of a base 51 that holds the optical mechanism 30 and a cover 52 that covers the optical mechanism 30 from the side opposite to the wall surface. A laser beam irradiation port 53 is formed in the cover 52 . The irradiation port 53 is open on the front side of the laser radar unit 20, on the side opposite to the fixed object 100. A transparent window panel 54 is fitted into the irradiation port 53, and the laser light from the optical mechanism 30 passes through the window panel 54 and is irradiated onto the area to be monitored (hereinafter referred to as the detection area). .

The optical mechanism 30 is housed in the housing 50, and irradiates laser light at each of the predetermined angles and receives the laser light reflected by the object S (hereinafter referred to as reflected light). The optical mechanism 30 includes a fixed mirror 31, a rotating mirror 32, and an optical block 33 consisting of a light projector and a light receiver. The fixed mirror 31 and the rotating mirror 32 form a part of the optical path P1 for guiding the laser beam output from the light projecting section to the outside of the housing 50, and an optical path for guiding the reflected light reflected by the object S to the light receiving section. It forms part of P2.

Specifically, the fixed mirror 31 is fixed to the housing 50 so as not to rotate, and the laser beam output from the light projecting section is reflected by the fixed mirror 31 toward the rotating mirror 32 side. The rotating mirror 32 is rotatable while maintaining a constant inclination angle with respect to the laser beam reflected by the fixed mirror 31. Specifically, a motor 34 (stepping motor), which is a driving means for the rotating mirror 32, is installed on the base 51. The output shaft (center axis CL1) of the motor 34 extends in the vertical direction, and the rotating mirror 32 is fixed to the tip of this output shaft. The motor 34 is connected to the control device and operates based on a drive signal from the control device. As the motor 34 operates, the rotating mirror 32 rotates (rotates) in the horizontal direction (scanning direction) in units of a predetermined angle. Note that the portion between the fixed mirror 31 and the rotating mirror 32 in the optical path P1 is configured to coincide with the central axis CL1.

The laser beam output from the light projecting section of the optical block 33 is reflected in the order of the fixed mirror 31 and the rotating mirror 32, and is irradiated to the outside of the laser radar unit 20 (detection area) through the window panel 54. When some object S exists on the optical path P1 of the laser beam irradiated to the detection area, the laser beam is reflected by the object S. The reflected light reflected by the object S enters the laser radar unit 20 through the window panel 54 and is reflected in the order of the rotating mirror 32 → the fixed mirror 31, and the reflected light reflected by the fixed mirror 31 is transmitted to the light receiving section of the optical block 33. Head to.

The laser radar unit 20 is provided with a drive circuit (not shown), and the above-mentioned control device is connected to this drive circuit. An optical mechanism 30 (a motor 34 and a light projector) is connected to the drive circuit, and the drive circuit controls the optical mechanism 30 based on commands from a control device and the like. The control device is provided with a control section and a storage section. The storage unit stores a control program for the laser radar and various measurement results obtained from the laser radar unit 20. The control unit determines the presence or absence of the object S in the detection area, calculates the distance to the object S, etc. based on the measurement results stored in the storage unit, such as the intensity of the reflected light and the time difference from the output of the laser light to the reception of the light. I do.

Next, the optical block 33 will be explained with reference to FIGS. 2 and 3. In addition, in FIG. 3, illustration of the case for the optical block 33 is omitted.

As shown in FIG. 2, the optical block 33 includes a light emitting element 36 that is a light source of laser light, a cylindrical light projecting lens 37 that defines a laser light projecting axis AX1, and a light receiving lens that collects reflected light. 39, and a light receiving element 38 that receives the reflected light collected by the light receiving lens 39. The light emitting element 36 and the light projecting lens 37 constitute a light projecting section 33a, and the light receiving element 38 and the light receiving lens 39 constitute a light receiving section 33b.

The light projecting section 33a and the light receiving section 33b are arranged vertically in parallel so that the light projecting section 33a is on the lower side and the light receiving section 33b is on the lower side. The light receiving axis AX2 is non-coaxial. Specifically, the light-emitting axis AX1 of the light-emitting lens 37 and the light-receiving axis AX2 of the light-receiving lens 39 are parallel, and the light-receiving axis AX2 is offset upward (upper side in the juxtaposed direction) with respect to the light-emitting axis AX1. (See Figure 3). That is, in this embodiment, a parallax PX is provided between the light emitting axis AX1 and the light receiving axis AX2.

One of the features of this embodiment is the configuration related to the light receiving lens 39. The light receiving lens 39 will be supplementarily explained below with reference to FIGS. 2 to 4.

As shown in FIG. 2, the light-receiving lens 39 is a plano-convex lens having a convex surface 41 and a flat surface 42, with the flat surface 42 facing the light-receiving element 38 side and the convex surface 41 facing the opposite side from the light-receiving element 38 side (fixed mirror 31 side). It is arranged so that it is facing the direction. In other words, the convex surface 41 serves as an incident surface for reflected light.

As shown in FIG. 3, the light-receiving lens 39 has a bottom surface (horizontal surface) facing toward the light-emitting section 33a at a portion below the light-receiving axis AX2 (on the light-emitter side). It is formed to have a substantially semicircular shape when viewed from the front (when viewed in the direction of the light receiving axis AX2). This is an idea to reduce the parallax PX (see FIG. 2) between the light emitting axis AX1 and the light receiving axis AX2, which are non-coaxial (offset relationship).

At the center of the convex surface 41 of the light-receiving lens 39, a convex portion 43 is formed that is convex on the side opposite to the light-receiving element 38 side. The convex portion 43 has a cylindrical shape coaxial with the light receiving axis AX2, and its length is smaller than the thickness of the light receiving lens 39 excluding the convex portion 43.

The portion of the convex surface 41 other than the convex portion 43 is a long-distance lens that guides reflected light from an object S located at a long distance from the laser radar device 10 (specifically, the laser radar unit 20) to the light receiving element 38. Approximately the upper half of the top portion 44 of the convex portion 43 also serves as a long-distance lens portion 47b that guides reflected light from a long distance to the light receiving element 38. Specifically, the long-distance lens parts 47a and 47b are aspherical surfaces that are rotationally symmetrical about the light-receiving axis AX2, and reflected light parallel to the light-receiving axis AX2 is guided to the focal point FP, that is, the light-receiving element 38. The configuration is as follows.

Here, the further the object S and the laser radar unit 20 are apart, the easier it is for the laser light (reflected light) reflected by the object S that has a smaller angle with the light receiving axis AX2 to reach the lens. In other words, the direction of the reflected light from the object S located far away from the laser radar unit 20 when it reaches the light receiving lens 39 is approximately parallel to the light receiving axis AX2, and the direction of the reflected light from the object S located far away from the laser radar unit 20 is approximately parallel to the light receiving axis AX2. When the reflected light from the existing object S reaches the light receiving lens 39, the angle it makes with the light receiving axis AX2 becomes large. In other words, the long-distance lens section 47a receives reflected light that forms a large angle with the light-receiving axis AX2, that is, from an object S located at a short distance from the laser radar device 10 (more specifically, the laser radar unit 20). The reflected light will be largely deviated from the light receiving element 38.

In the light receiving lens 39 shown in this embodiment, in order to supplement the detection function at the short distance where the long distance lens section 47 cannot detect the object S, approximately half of the lower side of the top portion 44 of the convex portion 43 is provided. A short distance lens section 48 is formed. The short-distance lens section 48 has a cylindrical aspherical surface centered on the central axis AX3, and is constituted by a semicircular cylinder lens when viewed from the front of the light-receiving lens 39. The area occupied by the lens part 48 for short distances and the lens part 47b for long distances in the top part 44 are the same, and in FIG. The boundary portion is simply shown using a two-dot chain line. The area occupied by the short-distance lens section 48 on the convex surface 41 of the light-receiving lens 39 is smaller than the area occupied by the long-distance lens section 47. This was done in consideration of the fact that the amount of light reflected from a long distance tends to decrease due to diffusion.

The central axis AX3 is perpendicular to the light emitting axis AX1 of the light emitting part 33a and the light receiving axis AX2 of the light receiving part 33b. In other words, the short-distance lens part 48 has a curvature in the direction (horizontal direction) perpendicular to the central axis AX3 (see FIG. 5), but in the direction parallel to the central axis AX3 (vertical direction), it has a curvature. It has no curvature (see Figure 6). In other words, the direction perpendicular to the central axis AX3 (horizontal direction) is the so-called power direction, and the direction parallel to the central axis AX3 (vertical direction) is the so-called non-power direction.

Here, with reference to FIG. 7, a description will be given of how reflected light passes through the short-distance lens section 48. Note that FIG. 7 is a schematic diagram for explaining the function of the cylindrical short-distance lens portion 48, and for ease of understanding, the outer shape when viewed from the front is shown as a rectangle.

When the reflected light that enters the short distance lens section 48 is parallel light parallel to the light receiving axis AX2, the reflected light passes through the short distance lens section 48 and is condensed in the focusing range FL. . The condensing range FL has a linear shape parallel to the central axis AX3, and includes the focal point FP of the long-distance lens section 47. That is, the reflected light parallel to the light-receiving axis AX2 passes through the short-distance lens section 48, and a part of it is guided to the focal point FP (light-receiving element 38).

As described above, the short distance lens section 48 has a non-power direction in which the direction parallel to the central axis AX3 (vertical direction) does not function as a lens. Therefore, if the reflected light incident on the short-distance lens section 48 is non-parallel to the light receiving axis AX2, specifically, reflected light incident obliquely from below, the incident position and incident angle When these conditions are met, the light is guided to the focusing range FL, more specifically to the focal point FP. That is, for reflected light whose inclination with respect to the light receiving axis AX2 is non-parallel, even if the angle with respect to the light receiving axis AX2 becomes large to some extent, a part of the reflected light may reach the light receiving element 38. Considering that the reflected light is guided to the light receiving element 38 when the long-distance lens section 47 is parallel or substantially parallel to the light-receiving axis AX2, that is, it is easily influenced by the angle of the reflected light, the short-distance lens The lens characteristics differ in that the lens section 48 has weaker restrictions on the angle of reflected light, and the long-distance lens section 47 has stronger restrictions on the angle of reflected light.

Next, with reference to FIG. 8, a supplementary explanation will be given of the difference in light reception mode between reflected light from a long distance and reflected light from a short distance.

As described above, the reflected light from a long distance is approximately parallel to the light receiving axis AX2. Therefore, as shown in FIG. 8A, most of the reflected light incident on the long-distance lens section 47 is guided to the light receiving element 38 through the long-distance lens section 47. Also, a portion of the reflected light incident on the short-distance lens section 48 is guided to the light receiving element 38. This prevents the provision of the short-distance lens section 48 from becoming a factor in reducing the light reception efficiency of reflected light from a long distance.

On the other hand, for reflected light from a short distance, the inclination with respect to the light receiving axis AX2 becomes large. Therefore, guidance by the long-distance lens section 47 is virtually impossible. However, as shown in FIG. 8(b), a part of the reflected light incident on the short-distance lens section 48 is guided to the light receiving element 38. In addition, a part of the reflected light from a short distance may be totally reflected by the side surface 45 of the convex portion 43 and reach the light receiving element 38, and it is possible to increase the amount of light received by adding the total reflection. ing. In addition, in FIG. 8(b), the optical path when it is assumed that the short-distance lens section 48 is replaced with the long-distance lens section 47 is illustrated by a two-dot chain line.

Next, with reference to FIGS. 9 and 10, the benefits of the short-distance lens section 48 (convex section 43) will be explained based on the relationship between the distance to the object S and the amount of received light. FIG. 9 is a schematic diagram showing a comparative example. In the optical block 33X shown in the comparative example, the configuration corresponding to the convex portion 43 is omitted, and the entire convex surface 41X of the light receiving lens 39X is used as the long-distance lens portion 47X. It has become. In other words, unlike the optical block 33 shown in the present embodiment, the structure is not intended for bifocal use. Note that the configuration of the optical block 33X other than the light-receiving lens 39X is the same as that of the optical block 33 described above, so a description thereof will be omitted.

As shown in FIG. 10, in the optical block 33X that is a comparative example, the amount of light received at short distances is almost 0. In other words, objects S located near the laser radar device 10X are not detected. On the other hand, in the optical block 33 shown in this embodiment, the amount of light received at short distances is significantly increased, and the object S can be detected even in the vicinity of the laser radar device 10. In other words, it is possible to detect the object S even at a short distance that cannot be handled in the comparative example.

Here, at long distances, although the amount of light received by the optical block 33 shown in this embodiment is slightly lower, the amount of decrease is negligible compared to the threshold value that is the criterion for detection. This suppresses the decline in detection accuracy over long distances. Note that the threshold value serving as the determination standard is set in consideration of the influence of disturbance, and when the amount of received light exceeds this threshold value, it is determined that the object S exists.

Incidentally, assuming that the light receiving lens 39 and the light receiving element 38 shown in this embodiment are, for example, a light receiving lens with a diameter of 50 mm and a light receiving element 38 with a diameter of 1 mm, if the distance to the object S is within 1.5 m, which is a short distance, Detection of the object S becomes substantially difficult due to the insufficient amount of received light. In this way, when the entire entrance plane is made up of a long-distance lens section, the range in which reflected light cannot be substantially focused corresponds to the "near distance" shown in this embodiment, and the range beyond that Distance corresponds to "long distance". That is, in the above specific example, a distance of 1.5 m or less is a "near distance", and a distance greater than 1.5 m is a "long distance".

According to the first embodiment described in detail above, the following excellent effects are achieved.

In order to improve the detection accuracy by increasing the amount of reflected light received from the object S located at a long distance, it is preferable to make the light emitting axis AX1 of the light emitting part 33a and the light receiving axis AX2 of the light receiving part 33b parallel. preferable. However, when the direction of the light emitting axis AX1 and the direction of the light receiving axis AX2 are aligned in this way, the reflected light from the object S located at a short distance will be reflected from the viewing range where the light can be received by the light receiving part 33b. It will come off easily. This is not preferable in terms of increasing the amount of reflected light received from the object S located at a short distance. For example, although it is possible to increase the amount of light received by increasing the size of the lens section for close-range use, this approach increases the size of the lens itself or takes up space for the lens section for long-distance use. It becomes a factor. As described above, there is still room for improvement in the configuration in order to improve the detection accuracy of the object S located at a short distance while suppressing the decrease in the detection accuracy of the object S located at a long distance. In this regard, in the laser radar device 10 described above, the short-distance lens section 48 is configured to allow reflected light (non-parallel light) from a short distance to reach the light-receiving element 38, while allowing reflected light (parallel light) from a long distance to reach the light-receiving element 38. The structure is such that light (light) can also be guided to the light receiving element 38 through the short-distance lens section 48, and while the object S can be detected at a short distance, the presence of the short-distance lens section 48 prevents reflected light from a long distance. This prevents this from becoming a factor that significantly reduces the amount of light received. Thereby, it is possible to suitably widen the detection area of the object S in the bifocal laser radar device 10.

Note that by offsetting the light receiving axis AX2 with respect to the light projecting axis AX1, it is possible to prevent the light projecting system such as the light projecting element from becoming a shadow and reducing the amount of light received. This is preferable in order to improve the detection accuracy of the object S. However, in such a configuration, the angle of the reflected light with respect to the light receiving axis AX2 becomes larger as the distance to the object S becomes shorter, and the amount of change in the angle also becomes larger. In this embodiment, in particular, the short distance lens section 48 is configured to allow reflected light (non-parallel light) from a short distance to reach the light receiving element 38, while also allowing reflected light (parallel light) from a long distance to reach the light receiving element 38. By adopting a configuration in which light can be guided to the light receiving element 38 through the near-distance lens section 48, and by suppressing the presence of the near-distance lens section 48 from becoming a factor that greatly reduces the amount of reflected light received from a long distance, In the dual-use laser radar device 10, the detection area of the object S is suitably widened.

In the light-receiving lens 39, which is a plano-convex lens, the short-distance lens portion 48 is formed to be convex on the same side as the convex surface 41, which is the incident surface of the laser beam, and the light-receiving element 38 side is a flat surface 42. The light-receiving lens 39 can function like a flat plate whose direction (inclination) in the vertical direction does not change when the reflected light passing through the short-distance lens section 48 is targeted. With such a configuration, even if the incident position in the vertical direction is different, the direction of the reflected light can be suppressed from changing significantly before and after passing through the short-distance lens section 48, and the reflected light from a short distance can be The function of causing the light to reach the light receiving element 38 can be suitably performed.

When the configuration is such that the reflected light from a short distance reaches the light receiving element 38 through the cylindrical short distance lens section 48, a short distance light is provided at a portion of the light receiving lens 39 that is closer to the light projecting section 33a than the light receiving axis AX2. By configuring the structure in which at least a portion of the lens portion 48 is located, it is possible to suitably improve the light reception efficiency of reflected light from a short distance.

In a configuration in which the reflected light is guided to the light receiving element 38 by the light receiving lens 39, the light receiving efficiency may decrease due to increased manufacturing errors. Such concerns are expected to become stronger as the shape of the lens becomes more complex and molding becomes more difficult. In this regard, if the convex part 43 is formed on the incident surface of the light receiving lens 39 as described above, and the short-distance lens part 48 is disposed on the top part 44 of this convex part 43, for example, a concave part can be formed on the incident surface. Compared to the case where a short-distance lens part is formed at the bottom of this recessed part, molding of the light receiving lens becomes easier. Thereby, concerns caused by the combination of the long-distance lens section 47 and the short-distance lens section 48 can be suitably eliminated.

The convex part 43 has a cylindrical shape centered on the light receiving axis AX2, and the part of the top part 44 that is on the light projecting part 33a side with respect to the light receiving axis AX2 is connected to the short distance lens part 48 and the light receiving axis AX2. On the other hand, a portion opposite to the light projecting portion 33a side is formed to serve as a long-distance lens portion 47. With such a configuration, the outer diameter of the convex portion can be increased while suppressing the enlargement of the short-distance lens portion. This is preferable in order to improve the light reception efficiency of reflected light from a short distance by utilizing total reflection at the side surface portion 45 of the convex portion 43. In other words, it is preferable to improve the light receiving efficiency of reflected light from a short distance while suppressing a decrease in the light receiving efficiency of reflected light from a long distance.

It is preferable to form the short-distance lens portion 48 into a cylindrical shape in order to suppress the expansion of the field of view for receiving reflected light and to suppress a decrease in detection accuracy due to the influence of external disturbances and the like. In this embodiment, in particular, the direction in which the light emitting axis AX1 and the light receiving axis AX2 are arranged side by side and the axial direction of the central axis AX3 are configured to be perpendicular to the scanning direction of the laser beam. According to this configuration, it is possible to suppress the expansion of the field of view in the scanning direction. By suppressing the expansion of the field of view, it is possible to suppress false detection of the object S due to disturbances, etc., and contribute to improving the detection accuracy of the position of the object S in the scanning direction.

<Second embodiment>
As already explained, the optical mechanism 30 is housed in the housing 50, and the laser light output from the light projecting section 33a is irradiated onto the detection area through the window panel 54 of the housing 50. In such a configuration, a portion of the laser light that has entered the window panel 54 is reflected by the window panel 54 and can reach the light receiving element 38 via the rotating mirror 32 → the fixed mirror 31. Since the distance from the light projector 33a to the window panel 54 is extremely short, the amount of light detected when the reflected light from the window panel 54 reaches the light receiving element 38 increases.

As described above, the control unit of the laser radar device 10 calculates the distance to the object S based on the amount of light detected by the light receiving element 38, but the reflected light from the window panel 54 is not detected as if it were detected for the above reason. This may cause false detection as if the object S were present within the area. This is assumed to be a hindrance to improving the reliability of the laser radar device. The present embodiment differs in configuration from the first embodiment in that measures have been taken to suppress such concerns.

Specifically, as shown in FIG. 11, between the light-receiving lens 39 and the light-receiving element 38, the amount of light reaching the light-receiving element 38 is reduced by blocking a part of the reflected light that goes toward the light-receiving element 38 through the light-receiving lens 39. A diaphragm portion 61A is provided to reduce the. Regarding the reflected light from a short distance, the angle at which it enters the short distance lens section 48 changes depending on the distance from the light projecting section 33a to the reflection position. Therefore, the diaphragm section 61A is designed to block the reflected light that passes through the short-distance lens section 48, assuming the distance from the light projection section 33a to the window panel 54 (corresponding to the "predetermined distance"). Its size and shape are specified.

As shown in FIG. 12, in the optical block 33A to which the aperture section 61A is added, the amount of light received from near the window panel 54 is greatly reduced among the amount of reflected light received from a short distance. This suppresses the occurrence of the above-mentioned false detection due to reflected light from the window panel 54. In other words, while making it possible to detect the object S located at a short distance using the short-distance lens section 48, by controlling the amount of reflected light received from a short distance by the aperture section 61A, it is possible to accurately detect the object at a short distance. It improves its uniqueness. Thereby, the reliability of the laser radar device can be suitably improved.

Note that it is also possible to improve reliability by distinguishing the reflected light from the window panel 54 from other reflected light based on the amount of received light and the time difference from light emission to light reception. However, in such a configuration, high accuracy is required to grasp the time difference. In this regard, if the reflected light from the window panel 54 is dealt with using the aperture section 61A as shown in this embodiment, the above problem can be solved with a simple configuration.

<Other embodiments>
- In each of the above embodiments, the light projecting section 33a and the light receiving section 33b are arranged vertically so that the light projecting section 33a is on the upper side and the light receiving section 33b is on the lower side, but the present invention is not limited to this. . For example, they may be arranged vertically so that the light projecting section 33a is on the upper side and the light receiving section 33b is on the lower side. In addition, although the direction in which the light projecting section 33a and the light receiving section 33b are arranged is perpendicular to the scanning direction (horizontal direction) of the laser beam in the laser radar device 10, the direction in which the light projecting section 33a and the light receiving section 33b are arranged is It is also possible to arrange them in the same direction as the scanning direction (horizontal direction) of the laser beam in the device 10, that is, to arrange them side by side. Even when changing to these positional relationships, by providing the short-distance lens section 48 in the portion of the light-receiving lens 39 that is on the light-emitting section 33a (light-emitting axis AX1) side with respect to the light-receiving axis AX2, light reception can be improved. The light receiving efficiency in the element 38 can be suitably improved.

- In each of the above embodiments, the central axis AX3 of the cylindrical short-distance lens portion 48 extends in the direction (vertical direction) in which the parallax PX is generated between the light emitting axis AX1 and the light receiving axis AX2. Although it is desirable that the central axis AX3 extends in the vertical direction, if the focal point FP (light receiving element 38) of the long-distance lens section 47 is included in the condensing range FL of the short-distance lens section 48, This does not negate compositions that lean toward the opposite. However, in order to guide a part of the reflected light (parallel light) from a long distance to the light receiving element 38, it is preferable that the central axis AX3 be tilted in the vertical direction not in the left and right directions but in the front and rear directions.

- In each of the above embodiments, the light-receiving lens 39 is formed into a substantially semicircular shape when viewed from the front, and the gap (parallax) between the light-emitting axis AX1 and the light-receiving axis AX2 is reduced, but the present invention is not limited to this. It's not something you can do. Although the gap (parallax) between the light emitting axis AX1 and the light receiving axis AX2 becomes large, it is also possible to form the light receiving lens 39 in a circular shape when the light receiving lens 39 is viewed from the front.

- In each of the above embodiments, the short-distance lens portion 48 is provided in the portion of the light-receiving lens 39 that is on the light-emitting portion 33a side (the light-emitting axis AX1 side) with respect to the light-receiving axis AX2; however, the short-distance lens portion 48 It is sufficient that at least a part thereof is provided on the light projecting section 33a side (light projecting axis AX1 side) with respect to the light receiving axis AX2; This does not negate the provision of a close-range lens section on the opposite side.

- In each of the above embodiments, when the light-receiving lens 39 is viewed from the front, the outer peripheral part of the short-distance lens section 48 has an arc shape centered on the light-receiving axis AX2, but when the light-receiving lens 39 is viewed from the front, The shape of the outer periphery of the short-distance lens section 48 when viewed is arbitrary. For example, it is also possible to have an angular configuration.

- In each of the above embodiments, the light-receiving lens 39, which is a plano-convex lens, is arranged so that the plane 42 faces the light-receiving element 38 side, but it can also be arranged so that the convex surface 41 faces the light-receiving element 38 side. However, in the case of such a configuration, the reflected light (parallel light) incident from the plane 42 side enters the plane 42 perpendicularly, so that the light condensing function does not act on the plane 42. That is, the light is focused only by refraction by the convex surface 41 on the back side. If the light is greatly refracted at once in this way, large aberrations will occur, so it is assumed that it will be difficult to improve the light receiving efficiency in the light receiving element 38. Therefore, it is preferable to arrange the light receiving lens 39 so that the convex surface 41 becomes the incident surface of the reflected light as shown in the above embodiment.

- In each of the above embodiments, the short distance lens portion 48 is formed on the convex surface 41 side of the light receiving lens 39, but it is also possible to form the short distance lens portion on the flat surface 42 side. Specifically, while the short-distance lens portion is formed on the plane 42 side, the portion of the convex surface 41 that overlaps with the short-distance lens portion in the light-receiving axis AX2 direction is preferably a flat portion perpendicular to the light-receiving axis AX2. .

- In each of the above embodiments, a cylindrical convex portion 43 centered on the light receiving axis AX2 is formed on the convex surface 41 of the light receiving lens 39, and the long distance lens portion 47 (long distance lens portion 47b) is formed on the convex portion 43. Although the lens portion 47b for long distance and the lens portion 48 for short distance are provided together, it is not necessarily necessary to provide the lens portion 47b for long distance and the lens portion 48 for short distance. It is also possible to omit the long-distance lens section 47b. For example, the entire top portion 44 of the convex portion 43 may be used as the short-distance lens portion 48, or the portion of the convex portion 43 that is above the light receiving axis AX2 (the portion where the long-distance lens portion 47b is formed), Alternatively, it is also possible to delete (trim) the portion on the side opposite to the light emitting axis AX1 with respect to the light receiving axis AX2. Specifically, as shown in FIG. 13(a), the convex portion 43B may be configured to have a semi-cylindrical shape, and the entire top portion 44B thereof may be used as a short-distance lens portion 48B.

- In each of the above embodiments, the convex portion 43 is provided on the convex surface 41 of the light receiving lens 39, and a part of the top portion 44 of the convex portion 43 is formed into a cylindrical short-distance lens portion 48, but the present invention is not limited to this. isn't it. For example, as shown in FIG. 13(b), it is also possible to provide a concave portion 43C on the convex surface 41C, and make a part of the bottom surface portion 44C of the concave portion 43C a cylindrical short-distance lens portion 48C.

- In each of the above embodiments, the central axis AX3 of the short distance lens section 48 is perpendicular to both the light emitting axis AX1 of the light emitting section 33a and the light receiving axis AX2 of the light receiving section 33b. It is not limited. It is also possible to adopt a configuration in which the central axis AX3 of the short-distance lens section 48 obliquely intersects both the light projection axis AX1 of the light projection section 33a and the light reception axis AX2 of the light reception section 33b. That is, it is also possible to adopt a configuration in which the central axis AX3 of the short-distance lens section 48 is inclined toward the front side or the back side in the light receiving direction.

- In each of the above embodiments, the light emitting axis AX1 of the light emitting part 33a and the light receiving axis AX2 of the light receiving part 33b are configured to be parallel, but the laser beam from the light emitting part 33a can be received by the light receiving part 33b. If so, it is also possible to adopt a configuration in which the direction of the light emitting axis AX1 and the direction of the light receiving axis AX2 are deviated from each other.

- In the above embodiment, the light emitting section 33a and the light receiving section 33b are arranged vertically, but in the arrangement of the light emitting section 33a and the light receiving section 33b, the light emitting axis AX1 and the light receiving axis AX2 are not aligned. As long as they are coaxial, they may be changed arbitrarily. For example, it is also possible to arrange the light projecting part 33a on the upper surface of the housing 50 so as to face downward, and to arrange the light receiving part 33b on the back wall of the housing 50 so as to face forward. In the case of such an arrangement, it is preferable to form the short-distance lens section 48 in a portion of the light receiving lens 39 of the light receiving section 33b that is above the light receiving axis AX2 (a portion that is closer to the light projecting section 33a).

- In each of the above embodiments, the long-distance lens portion 47 is formed to have an aspherical surface that is rotationally symmetrical about the light-receiving axis AX2; It is also possible to form it into a spherical surface.

- In each of the above embodiments, the light receiving lens 39 is a plano-convex lens, but it is also possible to change this to a biconvex lens. However, in the case of such a configuration, the short distance lens section 48 is configured such that the angle of the reflected light before and after passing in the non-power direction of the short distance lens section 48 does not change depending on the incident position in the central axis AX3 direction. It is preferable to provide a flat portion on the convex surface on the light receiving element 38 side in a range through which the incident light passes.

- In each of the above embodiments, one light-receiving lens 39 (lens member) is provided with a long-distance lens section 47 and a short-distance lens section 48, but a lens member functioning as a long-distance lens section and a short-distance lens section are provided. The light-receiving lens may be configured by combining the light-receiving lens with a lens member that functions as a lens portion.

- In each of the above embodiments, a scanning type laser radar device is illustrated, but the optical mechanism 30 may be applied to a fixed type laser radar device other than a scanning type.

- In each of the above embodiments, the long-distance lens portion 47 is formed to have a rotationally symmetrical curved surface (aspherical surface), but a part of the long-distance lens portion 47 is formed to have a curved surface that is not rotationally symmetrical. may have been done.

DESCRIPTION OF SYMBOLS 10... Laser radar apparatus, 30... Optical mechanism, 33... Optical block, 33a... Light projecting part, 33b... Light receiving part, 36... Light projecting element, 37... Light projecting lens, 38... Light receiving element, 39... Light receiving lens (lens) or equivalent to a lens for a laser radar device), 41... Convex surface, 42... Plane, 43... Convex part, 44... Top part, 45... Side part, 47... Long-distance lens part, 47a, 47b... Long-distance lens part, 48...Near lens section, 61A...Aperture section, AX1...Light emitting axis (corresponding to the light emitting axis), AX2...Light receiving axis (corresponding to the light receiving axis), AX3...Center axis (corresponding to the center line), FP... Focal point, FL... focus range.

Claims (8)

A light projecting section that projects a laser beam, a light receiving section that has a lens that collects reflected light that is the laser light reflected by an object, and a light receiving element that receives the reflected light that is focused by the lens. , a laser radar device configured such that the light receiving axis of the light receiving section and the light emitting axis of the light projecting section are non-coaxial,
The lens includes:
a long-distance lens portion that has a curved surface that is rotationally symmetrical about the light-receiving axis and can guide reflected light parallel to the light-receiving axis to the light-receiving element;
The light receiving element has a cylindrical shape centered on a center line that intersects a straight line parallel to the light receiving axis, and a part of the reflected light parallel to the light receiving axis and a part of the reflected light not parallel to the light receiving axis are transferred to the light receiving element. A close-range lens part that can be guided to the
The light projecting section and the light receiving section are housed in a case body,
The case body is provided with a transparent part,
The laser beam projected from the light projecting section is emitted through the transmitting section,
Between the light-receiving element and the lens, a portion of the reflected light from the transmitting part and guided to the light-receiving element by the short-distance lens part is blocked, so that the light is transmitted to the light-receiving element. A laser radar device that is equipped with an aperture section that reduces the amount of reflected light that reaches it . The light receiving axis is offset in a predetermined direction with respect to the light emitting axis,
2. The laser radar device according to claim 1, wherein the short-distance lens section is formed such that the center line of the short-distance lens section intersects both the light projection axis and the light reception axis. The lens is a plano-convex lens, the convex surface of which constitutes the incident surface of the laser beam,
3. The laser radar device according to claim 2, wherein the short distance lens portion is formed to be convex on the same side as the incident surface. The lens is configured such that the center line of the short-distance lens section and the light receiving axis line are orthogonal to each other, and the focal point of the long-distance lens section is located in a linear condensing range of the short-distance lens section. The laser radar device according to claim 2 or 3, wherein the laser radar device is constructed as follows. The short-distance lens section is arranged such that at least a part of the short-distance lens section is located at a portion of the laser beam incident surface of the lens that is closer to the light emitting section than the light receiving axis. The laser radar device according to any one of claims 1 to 4 . A convex portion that is convex on the side opposite to the light-receiving element is formed on the incident surface of the laser beam of the lens, and at least a part of the top of the convex portion serves as the short-distance lens portion. The laser radar device according to any one of claims 1 to 5 . The light receiving axis is offset in a predetermined direction with respect to the light emitting axis,
The convex portion has a cylindrical shape centered on the light receiving axis,
The top portion of the convex portion has a portion on the side of the light emitting axis with respect to the light receiving axis as the short distance lens portion, and a portion on the opposite side of the light emitting axis with respect to the light receiving axis as the short distance lens portion. It is formed to be a long-distance lens part,
The laser radar device according to claim 6 , wherein a side surface of the convex portion functions as a total reflection surface that totally reflects reflected light from a short distance toward the light receiving element. A scanning laser radar device that projects a laser beam to an irradiation angle set for each predetermined angle,
The light receiving axis is offset in a predetermined direction with respect to the light emitting axis,
According to any one of claims 1 to 7 , the predetermined direction and the direction of the center line of the short-distance lens section are configured to be a specific direction orthogonal to the scanning direction of the laser beam. The laser radar device described.

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